1. Field of the Invention
The present invention relates to a method of and an apparatus for adjusting an amount of light in an image exposure recording system which scans a recording medium with a light beam to record an image on the recording medium by exposure to the light beam.
2. Description of the Related Art
Heretofore, there have widely been used image exposure recording systems in which a light beam modulated by image information is deflected by a light deflector such as a galvanometer mirror or a resonant scanner, and applied to scan a recording medium such as a film that is being fed in one direction, in another direction substantially perpendicular to the direction in which the recording medium is fed, for thereby recording an image on the recording medium by exposure to the light beam.
The image recorded on the recording medium has its density depending on the amount of light of the light beam. Therefore, the amount of light of the light beam applied to the recording medium needs to be set highly accurately in order to obtain an image of desired density. When a laser beam whose amount of light has a Gaussian distribution is applied to record an image on a recording medium which produces a color upon being supplied with a light energy beyond a certain level, the amount of light of the laser beam needs to be set with high accuracy in order to achieve a desired coloring range.
It has been customary to adjust the amount of light of a light beam by inserting an optical filter such as an ND filter or the like which has its optical transmittance varying stepwise depending on the location on the optical filter, forming on a recording medium a test pattern which is area-modulated by varying the. position of the optical filter, and measuring the density of the test pattern to determine an amount of light that can achieve an optimum exposure state.
The accuracy of the adjustment of the amount of light according to the above process greatly depends on the resolution of the optical filter. Therefore, a highly expensive optical filter is required if the amount of light is to be adjusted to a nicety. However, it is very difficult to manufacture an optical filter which has a high resolution and a wide adjustment range. In addition, an expensive measuring unit is necessary to measure the density of an area-modulated screen-tint test pattern.
It is a general object of the present invention to provide a method of and an apparatus for adjusting the amount of light of a light beam to record a desired image in an image exposure recording system, highly accurately with an inexpensive arrangement without the need for a special measuring unit.
A major object of the present invention is to provide a method of and an apparatus for adjusting the amount of a continuously oscillating light beam effectively and highly accurately in an image exposure recording system.
Another object of the present invention is to provide an inexpensive amount-of-light adjusting device having a means for modulating a light beam depending on an image to be recorded, doubling as a means for finely adjusting an amount of light, without increasing the number of components in an image exposure recording system.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which preferred embodiments of the present invention are shown by way of illustrative example.